"Our analysis suggests that, contrary to previous thinking, there is substantial value in bringing HRT with estrogen alone to the guidelines. The data show that for selected women it is not only safe, but potentially beneficial for breast cancer, as well as for many other aspects of women's health," said lead researcher Joseph Ragaz of the University of British Columbia.

"Over the last 30 years HRT has been used almost indiscriminately by women expecting the benefit of reducing cardiac risks, while providing a protective effect against bone fracture, and improving overall quality of life," said Ragaz.

The WHI HRT trial consisted of two cohorts of women; the estrogen-alone group of women without a uterus and the estrogen-plus-progestin group of women with a uterus.

The team found that subsets of women with no strong family history of breast cancer who received estrogen alone had a significantly reduced breast cancer incidence.

In addition, the 75 percent of women without benign disease prior to the trial enrollment also had a reduced breast cancer risk.

"Reduction of rates of breast cancer in the majority of women who are candidates for estrogen-based HRT is a new finding because estrogen was always linked with a higher incidence of breast cancer," said Ragaz.

The findings were presented at the 33rd Annual CTRC-AACR San Antonio Breast Cancer Symposium. (ANI)